1. Field of the Invention
This invention relates to a tape loading mechanism for a VCR (video cassette recorder), and more particularly, to a tape loading mechanism which draws a tape-like recording medium from a tape cassette loaded in a VCR, and winds the medium around a rotating head drum.
2. Description of the Related Art
In a tape loading mechanism for a VCR, in a loading method wherein, in general, a capstan is situated outside a running path of a magnetic tape, and a pinch roller for pressing the magnetic tape against the capstan is pressed against the capstan from the inside of the running path of the magnetic tape, it is necessary to move the pinch roller from an opening of a magnetic-tape cassette to a predetermined position and to accurately position it in accordance with a loading operation.
The following two kinds of structures have mostly been adopted for moving and positioning a pinch roller in a conventional tape loading mechanism of this kind:
(a) A structure wherein an arm rotatably supporting a pinch roller is rotatably pivoted on a movable base, and the pinch roller is positioned by moving the base and butting the arm against a stopper at a loading position.
(b) A structure wherein a supporting member pivoting a supporting arm of a pinch roller is moved by a moving mechanism, the supporting member is positioned by a pin secured on the supporting member being engaged with a catching member having a V-groove, and is charged by a spring.
Such structures, however, have the following disadvantages: It is difficult to provide a precise tilt angle of the pinch roller, that is, to secure so-called inclination accuracy at a catching position. Furthermore, inclination changes due to a reaction force when the pinch roller is pressed, and stable running of a magnetic tape is thereby hindered.
The structure of a pinch roller pressing mechanism generally adopted in a conventional VCR is shown in FIG. 1. In FIG. 1, there is shown a magnetic tape 4. A capstan 18 runs the magnetic tape 4 at a constant speed. A pinch roller 11 presses the magnetic tape 4 against the capstan 18. The pinch roller 11 is rotatably pivoted at an end portion of a rotatably-pivoted arm 98. In this structure, the arm 98 is pulled in the direction of arrow J by another member (not shown), a pressing force is given to the pinch roller 11 by a charging spring (not shown), and the pinch roller 11 is thereby pressed against the capstan 18.
In this structure, however, unevenness in the pressing force is produced along the vertical direction (the direction of the axis) of the pinch roller 11, hindering in some cases stable running of the magnetic tape 4. Accordingly, a structure as shown in FIGS. 2(A) and 2(B) has recently been adopted.
In FIGS. 2(A) and 2(B), a pressing lever 99 for providing a pressing force to a pinch roller 11 includes two contact members 99a and 99b, each having the shape of a projected piece, formed facing each other, and is lever 99 provided so as to be rotatable around a shaft 99c. The pinch roller 11 is supported by a rotable arm 98'. In this structure, by pulling the pressing lever 99 in the direction of arrow K in FIG. 2(A), the contact members 99a and 99b press upper and lower end portions 11a and 11b of the shaft of the pinch roller 11, respectively, to give a uniform pressing force to the pinch roller 11.
In the structure shown in FIGS. 2(A) and 2(B), however, if the contact members 99a and 99b of the pressing lever 99 are not aligned with each other, unevenness in the pressing force is produced along the direction of the shaft of the pinch roller 11. Accordingly, it is necessary to align the contact members 99a and 99b with each other in an assembling process of the VCR. Hence, this structure has the problems that it takes much time for the alignment, and production cost is thereby increased.